The invention relates to an apparatus for enveloping articles with a plastic foil, sheet or film, with a conveyor belt, which moves the enveloped articles up to and away from a welding device which can be moved up and down and which has a transverse welding member and at least one longitudinal welding member.
In a known apparatus of the aforementioned type, normally two foil webs are removed from two corresponding storage reels and are supplied to the welding device. Articles to be enveloped or packaged are introduced into the space between the two foils. Instead of using two foils, it is also possible to use a single foil, which is correspondingly deflected and folded. It is then necessary to laterally weld the foils (on one side only when the foil is folded) and between the articles. Thus, the term "foil" is understood to mean both a folded foil and two separate foils supplied in superimposed manner.
The welding process is preferably a separation welding process, so that the enveloped and packaged articles can be moved out of the apparatus for further treatment in the form of individual packs. The welding operation is carried out by welding members, which are pressed onto the foil from above. Corresponding abutments are provided below the foil. In a known apparatus of the aforementioned type, the feed process is interrupted during welding, i.e. the operation is intermittent, so as to obviate the need for moving the welding members with the foil and the articles during the short welding process.
An apparatus is known for processing and welding plastic foil hose portions, which have been previously cut to size and which are to be made into sacks or bags. For this purpose, the hose portions are fed to a welding device on a table, at right angles to their longitudinal axis, i.e. with their openings positioned laterally. The welding device is provided with transverse welding members, which are moved down onto the hose portions in order to produce a weld, but not a separation weld. Thus, during this welding process, the hose pieces are advanced to the next processing station on the table plate, the next processing station once again being a welding device for completing the welds. The drive and movement of the transverse welding members takes place with the aid of crank drives, positioned below the table plate. There is no conveyor belt. In addition, articles are not enveloped and instead only welds are produced, which welds do not simultaneously ensure a separation (West German publication Offenlengungsschrift No. 1,454,999).